Write logs.zip + logs to the correct place.

I erroneously assumed that the continuous builds don't set DIST_DIR,
whereas they do.

The variable naming is quite questionable, but for now, the important
thing is that the code works and I wanted to do that with the least
amount of change possible.

Also add some more logging:
- Shell environment
- Command line arguments
- Location of logs.zip
- The logs directory

Test: Presubmits.
Change-Id: I651b1045eeef568aa860fd2457fa7799ad68ba38